This invention generally pertains to hand manipulated instruments. More specifically, the present invention relates to a handle and jaws mechanism which can be adapted for use in a surgical instrument. The invention also relates to an intraocular lens and a method of using the instrument to implant the intraocular lens into the eye.
The invention is particularly applicable to a forceps-like instrument useful in cataract surgery, and will be described with particular relation thereto. However, it will be appreciated by those skilled in the art that the invention has broader applications and may also be adapted for use in many other hand manipulated instruments such as scissors and the like.
In the normal eye, light enters through the cornea, passes through the anterior chamber and pupil and is focused by the lens to form an image on the retina. The lens is surrounded by a capsule consisting of an anterior portion and a posterior portion. When the disease known as cataracts occurs, the lens becomes clouded or opaque. This interferes with transmission of light to the retina, and hence vision. The only known cure for cataracts is removal of the affected tissue. However, once the affected tissue has been removed from the eye, light entering the eye will not be properly focused on the retina without some artificial aid. Such aid can be provided by eyeglasses or by contact lenses; however, these aids do not provide satisfactory vision correction, comfort or convenience in most cases. Intraocular lenses, which are surgically implanted within the eye, have therefore become common as an alternative to eyeglasses and contact lenses.
As generally utilized in the ophthalmologic art, the term "intraocular lens" refers to an assembly including both a light focusing element or optic and haptics or support structures which serve to anchor the optic in place within the eye. Presently available intraocular lenses are commonly categorized as either "anterior chamber", "iris supported", or "posterior chamber".
The posterior chamber may be considered to be the most advantageous for intraocular lens implantation because the original lens was located in that chamber. However, it is also the most difficult and least accessible area for such implantation. Despite this, two types of posterior chamber lens implantation techniques have become common.
In an "extracapsular" procedure, only the nucleus and the anterior capsule of the eye are removed with the posterior capsule being left in place. Thus, the intraocular lens can be implanted "in the bag," i.e., the posterior capsule, or in front of the bag, in the sulcus.
Most conventional intraocular lenses need a special forceps-type instrument to grasp the lens during the process of positioning the lens in the eye. Such conventional forceps, however, do not preclude crushing damage to the haptic due to excessive handle compression by the surgeon. Existing intraocular lens forceps also do not have the capacity to allow for placement and release of the superior haptic (the lens support structure lying towards the patient's head) within the desired plane in a controlled and directional manner. To do so presently requires either a two-handed technique in which corneal, scleral or uveal tissue is directly manipulated with a second instrument or a torquing motion of the forceps and the intraocular lens during the release maneuver. Both of these are unnecessary and potentially hazardous.
In addition, no conventional forceps has the capacity for simultaneous iris retraction so that the anatomy in the eye can be seen by the surgeon during the lens implantation procedure. Therefore, both of the surgeon's hands are necessary and the surgeon must at times assume awkward hand positions.
Conventional posterior chamber lenses include the so-called "Shearing" lens which has two J-shaped resilient support members extending from its optic. The support members engage the wall of the eye or the ciliary sulcus immediately to the rear of the iris and effectively retain the optic against decentration (that is movement away from the center of the eye) or movement transversely of the axis of the eye. But, such conventional lenses do not have haptics which contact eye tissue over a wide area to maximize the distribution of haptic pressure and thus minimize tissue damage and to provide a stable intraocular support.
Accordingly, it has been considered desirable to develop a new and improved surgical instrument as well as a new and improved intraocular lens and method for implantation of the lens in the eye with the instrument which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.